How to use it

1. Drag this window onto the screen you want gone.
2. Pick a shade above; this page turns that colour so you can judge it. Pure black next to a bright film can be its own kind of glare, and a dark grey is often easier.
3. Press Go dark, or go straight there with a shade key: Q W E R for the presets, T for your own colour.
4. To come back: Esc, or double-click anywhere.

You are watching a film on the main screen. The second one is still lit: a chat window, a white document, a clock in the corner of your eye. Switching it off makes the desktop shuffle every window onto the remaining screen, and switching it back on shuffles them wrong.

So leave it on, and give it nothing to show. The cursor hides after a moment, and nothing else happens until you ask.

On an OLED screen the pixels are actually off. On an LCD the backlight stays on, so it is a very dark grey rather than black, which is still a lot better than a spreadsheet.